( Received on May 1, 2005 )

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1 Indian J Physiol Pharmacol 2005; 49 (3) : AN INVESTIGATION INTO THE ACUTE AND LONG-TERM EFFECTS OF SELECTED YOGIC POSTURES ON FASTING AND POSTPRANDIAL GLYCEMIA AND INSULINEMIA IN HEALTHY YOUNG SUBJECTS S. MANJUNATHA, R. P. VEMPATI, D. GHOSH* AND R. L. BIJLANI Department of Physiology, All India Institute of Medical Sciences, New Delhi ( Received on May 1, 2005 ) Abstract : The study was conducted to examine the hypothesis that yogasanas help in the treatment of diabetes mellitus by releasing insulin from the pancreas. Twenty healthy young voluntees (17 male, 3 female; age years) participated in the study. Each volunteer performed four sets of asanas in random order for 5 consecutive days each with a 2-day gap between consecutive sets of asanas. The four sets of asanas were : (I) dhanurasana + matsyendrasana, (II) halasana + vajrasana, (III) naukasana + bhujangasana, and (IV) setubandhasana + pavanamuktasana. Blood samples were collected on days 4 and 5 of each set of asanas for measurement of glucose and insulin levels before the asanas, within 10 min after performing the asanas, and 30 min after ingestion of 75 g glucose, which in turn was ingested immediately after the second blood sample. A standard 75 g oral glucose tolerance test (OGTT) was also done before and after the study. On the days of the pre-study or post-study OGTT, no asanas were done. The serum insulin levels after the asanas were lower (P<0.05) than those before the asanas. However, the serum insulin level 0.5 h after the post-asana oral 75 g-glucose challenge was higher (P<0.05) in Set IV than the 0.5 h postprandial insulin level in the pre-study OGTT; the same trend was observed in other sets as well although statistically not significant. The observations suggest that the performance of asanas led to increased sensitivity of the B cells of pancreas to the glucose signal. The increased sensitivity seems to be a sustained change resulting from a progressive long-term effect of asanas. The study is significant in that it has for the first time attempted to probe the mechanism by which yogasanas help diabetes mellitus. Key words : yoga insulin diabetes mellitus INTRODUCTION There are several studies suggesting a place for yoga in the management of diabetes mellitus (1 5). While details of the yogic intervention may differ widely, asanas *Corresponding Author : dghosh@aiims.ac.in

2 320 Manjunatha et al Indian J Physiol Pharmacol 2005; 49(3) (physical postures) are invariably at least one component of the intervention. Some yogic practitioners claim that a few selected asanas that involve twisting or folding of the abdomen are particularly beneficial in diabetes because they release insulin by compressing the pancreas (6). The present study was designed to examine this hypothesis, and to the best of our knowledge, is the first study to do so. In the present study, serum concentrations of insulin measured immediately after the asanas, and the insulinemic response to an oral glucose challenge after asanas was also evaluated in healthy young human subjects. In addition to these acute responses, the long-term effect of performing asanas for 4 weeks on glucose tolerance was also investigated. METHODS The study was done on 20 healthy young volunteers (17 male, 3 female; age year). All of them were non-smokers and non-alcoholics, and none of the female volunteers was pregnant. During the 4-week study period, every volunteer performed the following sets of asanas for 5 consecutive mornings each. Set I : Dhanurasana (Bow pose) and Ardhamatsyendrasana (Half spinal twist). Set II : Halasana (Plough pose) and Vajrasana (Thunderbolt pose). Set III : Naukasana (Boat pose) and Bhujangasana (Cobra pose). Set IV : Setubandhasana (Bridge pose) and Pavanmuktasana (Wind releasing pose). The asanas of sets I III were found to be effective in reducing fasting and postprandial glucose in diabetes by Sahay (1). The asanas in set IV are not specifically advised for diabetics, and served as controls. The volunteer performed a set of asanas from Monday through Friday. After a 2-day gap (Saturday and Sunday), he/she started with the next set of asanas. The sequence of the four sets of asanas was randomized. Blood samples were collected on days 4 and 5 (Thursday and Friday) of each set of asanas for measurement of glucose and insulin at the following time points : (a) (b) before the asanas within 10 min of finishing with the asanas. Since the subject came after an overnight fast for asanas, both (a) and (b) were fasting samples. After collecting sample (b), the subject was given a drink containing 75 g glucose dissolved in 300 ml water. A third blood sample was collected 30 min after ingestion of the glucose drink. An oral glucose tolerance test (OGTT) was done 2 3 days before and after the 4-week study. The experimental design has been shown below. Days 1 5, Monday Friday,, Blood samples; OGTT, Oral glucose tolerance test.

3 Indian J Physiol Pharmacol 2005; 49(3) An Investigation into the Acute and Long-term effects 321 The protocol On each of the days that the volunteer came for asanas, the sequence of events was as follows : Fasting blood sample* Breathing exercises : 5 min (a) Dog breathing (b) Tiger breathing Stretching exercises : 10 min Tadasana (Palm tree pose) Neck rolls Shoulder movements Arm rotation Elbow movements Finger movements Waist bends Knee rotation Ankle movements Asanas as per the Set : 10 min Each asanas for 30 sec at a time thrice with an interval of 1 min between the asanas. Shavasana (Corpse pose) : 5 min Blood sample within 10 min* 75 g glucose drink* Blood sample 30 min after the glucose drink* *Only on days 4 and 5 of each set Oral glucose tolerance test After having been on an unrestricted carbohydrate diet for at least 3 days, the subject reported after an overnight fast. The patient was made to sit peacefully in a comfortable environment for 30 min, and then a venous blood sample (fasting) was collected. Then 75 g glucose was dissolved in 300 ml of refrigerated cold water, lemon juice added to it, and the drink administered to the subject orally. Thereafter venous blood samples were drawn at 30-min intervals till 2 h after ingestion of the drink. Serum glucose Serum concentration of glucose was determined by the glucose oxidase method using kits obtained from Randox Laboratories Ltd., Antrim, U.K. The intra-assay and inter-assay coefficients of variation for glucose were 2.1% and 4.0%, respectively. Serum insulin Serum concentration of insulin was determined by radioimmunoassay using kits obtained from Medicorp, Canada. The intra-assay and inter-assay coefficients of variation for insulin were 3.6% and 5.6%, respectively. Estimates of insulin sensitivity Indices of insulin sensitivity were calculated using formulae for (i) homeostatic model assessment (HOMA) for insulin resistance (7), and (ii) quantitative insulin sensitivity check index (QUICKI) (8). Data analysis The glucose and insulin values before the asanas were compared with those after the asanas. The 0.5 h postprandial glucose and insulin after the asanas were compared with the 0.5 h postprandial glucose and insulin in the prestudy standard OGTT. All these comparisons were made by Student s t-test. The comparisons of the insulin values have been made for log-transformed values. The Ethics Committee of All India Institute of Medical Sciences approved the study. Volunteers were enrolled in the study after they had given their informed written consent for participation.

4 322 Manjunatha et al Indian J Physiol Pharmacol 2005; 49(3) RESULTS The characteristics of the subjects have been summarized in Table I. The serum concentrations of glucose and insulin before, and immediately after asanas have been given in Table II. There was no significant difference between the serum glucose levels before and immediately after the asanas. Further, the serum glucose 0.5 h after an oral 75 g-glucose challenge in case of the four sets of asanas was not significantly different from the 0.5 h postprandial plasma glucose level (mean ± SD, ± 36.7 mg/ dl) in the standard OGTT done before the study. However, the serum insulin levels after the asanas were significantly (P<0.05) lower than those before the asanas. Further, the serum insulin 0.5 h after the oral 75 g- glucose challenge in Set IV was significantly higher than the 0.5 h postprandial insulin level (mean ± SD, ± picomoles/ L) in the standard OGTT done before the TABLE I : Characteristic Characteristics of the subjects. Value (mean±sd) Age (years) 23.8±4.0 Height (m) 1.6±0.05 Weight (kg) 57.2±6.3 BMI (kg/m 2 ) 21.2±1.6 study. The trend was similar in Sets I, II and III, but the differences were statistically not significant. The results of standard OGTT done before and after the study have been given in Table III. Comparison of corresponding pre-study and post-study levels revealed a significant (P<0.05) difference only in case of the 0.5 h insulin levels. However, there was no significant change in area under the 2-h insulin curve (AUC). In order to examine whether the changes observed in Table II were specific to the asanas in the various sets, or had evolved over 4 week during the study, the same data has been analysed as a function of time from week 1 through week 4 as shown in Table IV. The trend towards a higher insulin level 0.5 h after the post-asana 75-g glucose challenge, as compared to the corresponding level before the study first appears in week 2. This difference is significant (P<0.05) in week 3, and the trend persists in week 4. As compared with the pre-study OGTT data, there was no significant change in HOMA and QUICKI estimates of insulin sensitivity during the study whether we consider individual sets of asanas, or the weekly progression, or the post-study OGTT. TABLE II : Glucose and insulin levels before and after various sets of asanas. Asanas Plasma glucose (mg/dl) Serum insulin (picomoles/l) Before asanas After asanas After glucose Before asanas After asanas After glucose Set I 83.9± ± ± ± ±35.6* 820.3±427.5 Set II 81.2± ± ± ± ±35.6* 814.5±368.1 Set III 83.8± ± ± ± ±37.9* 833.8±472.4 Set IV 76.4± ± ± ± ±56.4* 868.0± *P<0.05, as compared to Before asanas. + P<0.05, as compared to 0.5 h value in Pre-study OGTT (Table III). Values are shown as means±sd.

5 Indian J Physiol Pharmacol 2005; 49(3) An Investigation into the Acute and Long-term effects 323 TABLE III : Oral glucose tolerance before and after the study. Plasma glucose (mg/dl) Serum insulin (picomoles/l) Pre-study Post-study Pre-study Post-study Fasting 83.3± ± ± ± h 140.1± ± ± ±402.4* 1.0 h 128.8± ± ± ± h 107.0± ± ± ± h 100.0± ± ± ±211.9 *P<0.05, as compared to Pre-study. Values are shown as means±sd. TABLE IV : Sequential glucose and insulin levels before and after asanas. Period Plasma glucose (mg/dl) Serum insulin (picomoles/l) of the study Before asanas After asanas After glucose Before asanas After asanas After glucose Week ± ± ± ± ± ±359.4 Week ± ± ± ± ± ±434.6 Week ± ± ± ± ± ±363.0* Week ± ± ± ± ± ±494.4 *P<0.05, as compared to 0.5 h value in Pre-study OGTT (Table III). Values are shown as means±sd. DISCUSSION Since the serum insulin levels within 10 min of performing a variety of asanas were not higher than those before the asanas, there is no evidence for release of insulin from the pancreas as a result of performing the asanas. On the contrary, the insulin levels after the asanas were significantly lower after the asanas than before the asanas (Table II). Further, postprandial serum insulin 0.5 h after ingestion of 75 g glucose was higher after the asanas than the corresponding value in the OGTT performed before any set of asanas had been done. This difference was statistically significant only in Set IV, but the trend in other sets was also the same (Table II). These observations suggest that the performance of asanas led to increased sensitivity of the B cells of pancreas to the glucose signal. Performance of asanas in the fasting state was presumably accompanied by steady and accelerated utilization of glucose, but serum glucose did not fall significantly after the asanas. The reason possibly was that the B cells responded to accelerated glucose utilization with prompt decrease in insulin release. On the other hand, administration of 75 g glucose led to a prompt increase in insulin release in amounts greater than under similar circumstances before the subject had been initiated into any asanas. Thus the increased sensitivity of B cells to glucose which we have hypothesized seems to work both ways, reducing insulin release briskly when glucose level tends to fall, and increasing insulin release sharply when glucose level tends to rise. The next question which needs to be

6 324 Manjunatha et al Indian J Physiol Pharmacol 2005; 49(3) answered is whether the increased sensitivity of B cells is the acute effect of performing asanas, or whether it is a sustained change resulting from a progressive long-term effect of asanas. The latter seems to be the case because the higher insulin level at 0.5 h is observed also in the post-study OGTT, a day on which no asanas were done. Further, the progressive development of the effect is revealed when the results are arranged sequentially in terms of time (Table IV). The 0.5 h postprandial insulin levels are higher than the corresponding pre-study OGTT value from wk 2 onwards, but not in wk 1. Since the sets of asanas were done in a random sequence, the effect seems to be due to the progressive build up of enhanced sensitivity of B cells irrespective of the asanas done rather than the specific effect of any set of asanas. Thus, the results of the present study have challenged the explanation popular among yoga teachers that asanas help diabetes by releasing insulin. The study also suggests an alternative explanation in terms of the asanas enhancing the sensitivity of the B cells of the pancreas to the glucose signal. Although a variety of physical exercises are known to enhance the peripheral sensitivity to insulin (9), we have come across only one earlier study that has hinted at a change in the sensitivity of B cells as a result of a physical activity (10). Further studies are needed to examine how far the results of the present study are valid also for those having diabetes mellitus, specially because of the dramatic differences that have been reported earlier between diabetics and non-diabetics (11). ACKNOWLEDGEMENTS We are grateful to the Department of Ayurveda, Yoga, Unani, Siddha and Homeopathy (AYUSH), Ministry of Health, Government of India, for a research grant which made this study possible. REFERENCES 1. Sahay BK. Yoga and diabetes. J Assoc Physicians India 1986; 34: Monro R, Power J, Coumar A, Nagarathna R, Dandona P. Yoga therapy for NIDDM : a controlled trial. Complement Med Res 1992; 6: Jain SC, Uppal A, Bhatnagar SOD, Talukdar B. A study of response pattern of non-insulin dependent diabetics to yoga therapy. Diabetes Res Clin Pract 1993; 19: Rugmini PS, Sinha RN. The effect of yoga therapy in diabetes mellitus. New Approaches to Medicine and Health (NAMAH) 1995; 2: Malhotra V, Singh S, Tandon OP, Madhu SV, Prasad A, Sharma SB. Effect of yoga asanas on nerve conduction in type 2 diabetes. Indian J Physiol Pharmacol 2002; 46: Kumar V. Physical exercise and yoga. In: Ahuja MMS (ed.). Practice of Diabetes Mellitus in India. New Delhi: Vikas, Chapter 19, pp Mathews DR, Hosker JP, Rudenski AS, Naylor BA, Treacher DF, Turner RC. Homeostasis model assessment: insulin resistance and B cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia 1985; 28: Katz A, Sridhar SN, Abert P, Sumner AE, Quon MJ. Quantitative insulin sensitivity check index: a simple accurate method for assessing insulin sensitivity in humans. J Clin Endocrinol Metab 2000; 85: Henriksen EJ. Invited review: effects of acute exercise and exercise training on insulin resistance. J Appl Physiol 2002; 93: Dela F, Von Linstow ME, Mikines KJ, Galbo H. Physical training may enhance (beta)-cell function in Type 2 diabetes. Am J Physiol (Endocrinol Metab) 2004; 287: E1024 E Heding LG, Ludvigsson J. B-cell response to exercise in diabetic and non-diabetic children. Acta Paediatr Scand (Suppl) 1980; 283: